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International 3Rs Prize now open for applications. £30k prize (£2k personal award) for outstanding science with demonstrable 3Rs impacts.

NC3Rs | 20 Years: Pioneering Better Science
CRACK IT Challenge

RespiraTox: In silico model for predicting human respiratory irritation

X-ray graphic of an upper body

At a glance

Award date
January 2018 - June 2019
Contract amount


  • Replacement



Inhalation of chemicals can lead to local effects such as respiratory irritation, and acute and chronic inflammation. To date, there are no specific guidelines to identify respiratory irritants. The respiratory irritancy potential of chemicals is typically assessed and extrapolated from modified rodent acute inhalation toxicity studies. These studies use a large number of animals (up to 42 rodents for a single study) and have significant animal welfare concerns.

Dr Sylvia Escher (Fraunhofer ITEM, Germany) in collaboration with Dr Andreas Karwath (University of Birmingham) have developed a user-friendly Quantitative Structure Activity Relationship (QSAR) tool to reliably predict the respiratory irritancy potential of single chemicals and mixtures in humans, allowing the early identification of potential toxicities in candidate chemicals without having to use in vivo studies.

Full details about this CRACK IT Challenge can be found on the CRACK IT website.